It's a gamble, especially if you have miniscule holes in your rings or seals that you'd otherwise never know about. The synthetic oil will 'clean out' the deposits that have clogged them and prevented oil from leaking and will cause a lot of oil burn off. I took the gamble at 165k miles. With regular dino oil I burned about a quart every 2k miles...switched to Castrol Syntec 5W-30, oil consumption went down to a quart every 3-4k miles. Now I'm with Mobil1 Full Synthetic and I'm down to about half a quart at 8k miles, which is pretty amazing. I'm not sure why there's such a difference but I think it has a lot to do with the inherent nature of VTEC engines, meaning they do burn the oil when pushed. I think my seals and rings must be in great shape but somehow my engine reacts better to the synthetic oil...I dunno, I've tried to figure it out and I have no idea. But for me the Mobil1 is worth it based purely on how much oil I was burning before.